Protective arrangement for electric installations



March 31, 1931. u. MODIGLIANI PROTECTIVE ARRANGEMENT FOR ELECTRICINSTALLATIONS Filed Dec: 6, 1923 -4 Shets-Sheet 1 M r 1931- u.MODIGLIANI ,7

PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec. 6, 1923 4Sheets-Sheet 2 gwq doz UMBERTO MOD/GL/A NI March 31, 1931. u MODIGLIANI7 PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec. 6, 19234Sheets-Sheet s I 11 III UMBE'HTO MOD/GL/AN/ March 31, 1931. u.MODIGLIANI PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec.6, 1923 4 Sheets-Sheet 4 I H H gwue/nliot UMBEHTO MOD/GL/AN/ FIG. 5

Patented Mar. 31, 1931 UNITED STATES UMBERTO MODIGLIANI, OF MILAN, ITALYIRO'IEC'JJIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Application filedDecember 6, 1923, Serial No.

The present invention relates to a protective arrangement for electricinstallations operating in such manner as to control the opening ofinterrupters arranged so as to permit the separation from theinstallation of the parts of circuits wherein a derangement takes place.This arrangement consists substantially in the combination of aplurality of elementary relays grouped so as to form a combination ofrelays adapted to be considered as a multiple relay, each of which isactuated by any kind of electric action exerted thereon by the currentscirculating in the installation. This action is of amperemetriccharacter if the relay is actuated by a current the intensity of whichis proportionalto the intensity of the current to be controlled; it isof voltmetric character if the relay is actuated by a current theintensity of which is proportional to the tension of the current to becontrolled; and it is of watt-metric character it" the relay is actuatedby two combined actions, one amperemetric and the other voltmetric,which gives a resultant proportional to the rate of flow of energy.

This arrangement is characterized by the combination of a plurality ofelementary relays into a multiple relay, each elementary relay beingactuated by any kind of electric action of the currents to becontrolled, and said current-s may differ from one another as to theircharacter, phase and frequency. Said elementary relayscomprise each anelectric meter or measuring instrument adapted to give a mechanicalaction proportional to the tension or to the intensity or to the power,or to any other electric quantity of the current to be controlled,according to their winding being voltmetric or amperemetric orwattmetric; and means adapted to oper ate a switch interrupting saidcurrents, when these currents, which normally must be balanced, i. e. ina predetermined ratio between each other, become unbalanced.

For this purpose there are provided means for mechanically connectingseveral relays with each other in such manner that when all of thecurrents energizing said relays are nearly balanced, that is, in aconstant predetermined ratio between each other, said 679,025, and inGermany December 14, 1922.

means for operating the switches remain inoperative when on the otherhand, one of said currents becomes unbalanced, so that its quantity(tension, strength, power be different from'that which is in saidpredetermined ratio with respect to the same quantity of the othercurrents, said means become operative and control the switch.

The invention also relates to a combination of a plurality ofdifferential elementary relays forminga retarded operation multiplerelay, with a plurality of interrupters and with means adapted to locksaid interrupters when the multiple relays cause the starting of one ofsaid control interrupters governing a circuit in which a derangement"has taken place, this locking ceasing only when said latter interrupteris open.

In order to construct the device, it is necessary that the circuits tobe protected be provided with interrupters adapted to open by thepassage of an auxiliary current into the opening electromagnet, thiscurrent being supplied by the relay at the proper moment.

The protective device of the present invention may be used with singlelines or with a group of lines terminating at the same bus bars, or withmachines or with lines connect-ed together in parallel at their twoends, and it is always formed of the same elementary device, but groupeddifferently according to the case.

Referring to the drawings:

Fig. 1 is a diagram of the mechanicalcombination of three elementaryrelays and a locking device. 7

F ig.. 2 is a diagrammatic showing of three elementary relays;

Fig. 3 is a diagrammatic showing of the protective arrangement "appliedto three three-phaselines terminating at the same bus bars andconstructed for opening the interrupters interdependently. y

Fig. 4 is a diagram of three three-phase lines connected in parallel tothe same bus bars, with three multiple relays for openingthe'interrupters when an unbalance occurs.

Fig. 5 is a diagram of three three-phase lines connected to the same busbars operat ing in parallel with the current transformers connectedtogether so as to effect automatic opening during an unbalance and for apredetermined value of the total current.

Fig. 1 shows three elementary relays R R and R and a locking apparatusM, connected rigidly on two supports T. The elementary relay, which isthe most important device of this invention, is shown in each of thethree parts of Fig. 2. The same reference characters designate thevarious elements in Figs. 1 and 2. The elementary relay com prises ametallic disc 11 mounted on a shaft 10 set in rotation by electro-magnet12 and g 12 and is subject to the action of the permanent magnet 13 asin any ordinary electric meter. The shaft 10, which rotates in supports14. is of two parts connected together by the joint 15, which permitsthe upper part to be raised while allowing it to remain operativelyconnected with the lower part by sliding on pins 16. The lower part ofshaft 10 carries at its upper end a disk 15a to which pins 16 aresecured. The lower end of the upper part of shaft 10 carries a disk 15?)which is provided with two holes for receiving pins 16. By thisconstruction the two parts of the shaft are held against relativerotation, but the upper part may be moved axially with respect to thelower part. The upper part of the shaft carries an endless screw 17whose threadhas an inclination lower than the frictional angle(irreversible screw) which may rotate shaft D, by means of the toothedwheel (gear) 21 and couple 21 and 21 when in mesh through the action ofthe magnetic clutch 22. The pitch of the thread on screw 17 is such thatshaft D can be rotated by revolving shaft 10, but screw 17 cannot berotated by revolving'shaft D. When the upper part of shaft 10 is raisedby causes hereinafter set forth, contact 0 closes (Fig. 1, this isproduced by raising lever 23 pivoted at 24:).

There may be mounted on the same shaft D two or more wheels 21 actuatedbytwo or more elementary relays R and R ete., constructed and regulatedin the same manner and traversed by currents in the same direc tion soas to rotate the endless screw 17 in the direction for which they wouldcausethe upper part of shaft 10 to raise if wheels 21 were stopped, andwhich we call the positive rotational direction; if wheels 21 and 21 arein mesh, shaft D rotates at a velocity whichis a function of thecurrents, and if said currents are equal, nothing else will happen; butif the two currents become unequal, more exactly, if the current whichacts on B becomes the stronger one, the shaft R will have a tendency torotate more rapidly R; from above downwardly; but since the pitch ofthis screw is almost irreversible this force will have almost no effecton B Shaft D cannot rotate at a speed greater than that which R permits,and wheel 21 of R connected to shaft D will rotate at this same speed(in view of the ratios of the gears being equal) therefore, when theendless screw of R has a velocity greater than that of R it will appearas if wheel 21 were immovable and screw 17 of R rotates with a speedequa to the difference between the actual speed of R and the actualspeed of R i. e., screw 17 moves upwardly on account of its threadrevolving on teeth of wheel 21 and the upper part of shaft 10 raises andoperates contact 0 which, completing the auxiliary circuit, operates theauxiliary elements which, in turn, open the interrupter which should beopened, as set forth more clearly hereinafter. The length of endlessscrews 17 is suchthat they remain engaged with wheels 21 even when theshaft is raised. If the elementary relays are traverses by currents soas to rotate in the direction opposite to that which we have discussed,that is to say in the negative rotational direction, and so long as thecurrents, and their driving couples, are equal, shaft D will rotate inthe direction opposite that of the preceding case without operating anyswitch. But, if the current acting on R is less than the other, theendless screw of R, will have a tendency to rotate more slowly than thatof R shaft D, actuated by R operates wheel 21 of R at a speed greaterthan it would ha Y if itwere merely actuated by the endless screw of Rthe endless screw of R which cannot, in its rotation, follow the passageof the teeth of wheel 21, will be raised with the upper part of shaft 10from R making the contact 0. The same thing occurs if the motor coupleacting on B becomes zero or changes direction.

The driving couple which electromagnets 1.2 exert on disc 11 and shaft10 may be made proportional either to the tension or to the intensity orto the power of the current energizing said electromagnets. This dependson the windings of said magnets being voltmetric or amperemetric ones,or said magnets being coupled in order to give a wattmetric resultant.Said windings may, of course, be connected directly to the conductors ofthe electric installation one wishes to protect, or-there may beprovided instru ment transformers, i. e., voltage and currenttransformers, for keeping the relays of the protecting arrangementremoved from the high tension of the installations.

Where direct current is used it is necessary to add to the metallic disc10 a suitable winding on the same shaft, the same as in dire t currentmeters.

The operation of the elementary relays is always differential, whetherthe rotation of the shaft be positive or negative, and whatever may bethe number of elementary relays connected to the same shaft D. The ab-As has been stated, the absolute value .of the currents or of theenergles which traverse the conductors is of no importance, and

only the unbalance between these values of different conductors producesthe protective operation. g

' If it is desired to protect electric lines connected in parallel attheir two ends the elementary relays should be grouped differently. Fig.4 shows a station G from which depart three three-phase lines L L Lconnected to the same bus bars I, II and III; 1, 2, 3 are the conductorswhich pass to the elementary relays; A A A and B B B re spectively arethe opening interrupters and electromagnets controlled by the elementaryrelays, either directly or through timing devices. Fig.5 shows thestation F receiving the above mentioned lines L L L connected to the.same bars; 1, 2, 3 are the conductors passing to the elementary relays;A A A and B B B" respectively are the interrupters and. eleotromagnetscentrolled by the elementary relays; the interrupters may also be openedby the electromagnets K described hereinafter. The nine elementaryrelays which should be mounted in each station are divided into threegroups, and each group may be called a phase relay and comprises threeelementary relays connected to three conductors (one for each line)which are of the same phase; if there are 01. lines in parallel eachphase relay will have n elementary relays.

The elementary relays of the same phase are connected to the same shaftD and are subject to the action of block M and shaft H. For example,relays R 'R and R connected to the conductors of phase one, areassociated with shaft D and controlled by a common locking magnet M onshaft Hr. Assuming that the energy flows from G to'F the elementaryrelays are provided with magnetic clutches and have. windings of theamperemetric type arranged for positive rotation at G, and for negativerotation at F, and are connected to the conductors by currenttransformers T. If thethree lines which connect stations G and F are inserviceable condition, and if interrupters A are closed, the threecurrents of each phase will be equal (assuming the lines being equal; incase they Weredifferent the windings of the elementary relays wouldbesuitably constructed) and the three elementary relays of each of thethree phase relays would rotate at equal speeds Consequently, in stationG, the current in Wire ,L becomes greater, since the sense of flow ofcurrent remains the same; in station F, since the senseof the shortcircuit current is inverted with respect to the normal current, thereshall be an inversion of said :current, or, at leas t,.a reduction ofit.

I have statedthat for carrying out such a protection of multiple feeder,the multiple relays must bearranged forpositive rotation, i. e.,operation through excess of current, at station G and for negativerotation, i. e., operation through reduction of current, at station F.Indeed,in these conditions at station G the above-mentioned increaseofcurrent of wire L with respect to wires L" and L makes relay R closecontacts C and operate switch A of line L, thusdisconnecting-these linesfromthe bus bars. At station F, where the relays rotate negatively, theabove-mentioned reduction or inversion of current in Wire L makes therelay R close its contacts and operate switch A thus disconnecting lineL from the bus bars. Now the shortcircuit is completely isolated and thewhole system becomes balanced again, while. each of the unfaultylinesassumes a part of the load previously carried by the isconnected line. 1

Generally, when such a fault on a phase of a line occurs which resultsin an abnormal current flowing in the. conductor of that phase of thatline, the conductors of the same phase of the other lines becometraversed by an abnormal current, although less than that of the faultyline, since they are connected to the same bus bars.

In the above case, relays R R of these conductors begin to raise, likerelay R' but with a lesser speed, so that contacts C become closedbefore relays R R have reached their upper positions. As soon as 0 2close the tripping circuit, locking devices M become energized andprevent any further raising of relays R R In such manner, there isavoided the disconnecting of lines L and L on account of the transientunbalance and overload which occurs upon a fault on line L but whichdisappearsas soon as faulty line L isdisconnected, from the bus bars.

As soon as said faultyline is disconnected, the current therein drops tozero and the magnetic clutches of the relays energized by said linedisconnect said relays from the common shaft D. Thus the multiple relaycontinues to rotate and protect the lines still connected with the busbars and carrying currents. At the same time, locking means M becomede-energized and allow anyrelay to close contacts C; but now in generalthe remaining lines will be balanced; i. e., all of their conductorswijll carry-about the same current, and no relay will raise. Thus a ersin which the energy flows sometimes in one sense and sometimes in theother, one may carry it out simply on energizing wattmetrica-lly eachrelay. If, for example, one has two stations G and F and three feeders LL and L connecting said stations and carrying current alternatively fromG to F and from F to G, one may provide each of said stations with amultiple relay as described above, comprising a relay energizedproportionally to the rate of flow of energy in a conductor, andelectromagnetic clutches for disconnecting a relay from the shaft D whensaid relay stops, its conductor being disconnected from the system. Thusat the station supplying energy operation of the line breakers willoccur on account of an excess of current in any conductor, and at thereceiving station on account of avdrop of the received current or of areversal of its sense of flow, what actually occurs in case of a faultprotection will then be assured in any case.

The above mentioned protection may function only by reason of unbalancebetween the conductor currents, but not for excess load. If it isdesired to open the interrupters also for a predetermined load, andwhere current transformers have been mounted for said protection,thesecondaries of the transformers of the same phase may be connected inparallel through the winding of maximum relay MR, which causes all themterrupters to open at the same time, by means of electromagnets K,connected in circuit with battery Ba. The advantage of this apparatus isthat of op eration for the same excess load for which it is adjusted,whatever may be the number of the lines in operation.

What I claim is:

'1. The combination, in an electrical power transmission systemincluding a plurality of parallel conductors passing in groups throughswitches, electroresponsive devices each comprising an electric meteroperatively energized by one of said conductors, a shaft operativelyconnected with said meter and adapted to be moved by said meter at aspeed in direct relationship with an electric quantity of theelectricity flowing in said conductor, so that said speed beingcompelled to vary results in a torque proportional to said quantitybeing applied to said shaft, a plurality of said devices arranged in agroup, means adapted to connect mechanically allv of the shafts of agroup of said devices with each other and adapted to be moved by saidshafts which rotate at speeds in a constant predetermined ratio betweeneach other, but incapa- "le of driving said shafts, so that a shafttending to vary its speed results in said torque being applied to saidshaft, means controlled by said shafts and adapted to operate theswitches of a group of conductors when the shaftof an electroresponsivedevice con: nected wit-h a conductor of said group rotates at a speedwhich diflers from that corresponding in the predetermined ratio to thespeeds of the shafts of the other electroresponsive devicesof the samegroup, means adapted to regulate the amount of the torque exerted'onsaid shaft by which the operation of said switches occurs.

2. The combination, in an electrical power transmission system includinga plurality of parallel conductors passing in groupsthrough switches,electroresponsive devices each comprising an electric meter operativelyenergized by one of said conductors, a shaft operatively connected withsaid meter and adapted to be moved by said meter at a speed in directrelationship withan electric quantity of the electricity flowing in saidconductor, so that said speed being compelled to vary results in atorque proportional to said quantity being applied to said shaft, aplurality of said devices arranged in a group, means adapted to connectmechanically all of the shafts of a group of said devices with each edwith a conductor of said group rotates at a speed which differs fromthat corresponding in the predetermined ratio to the speeds of the otherand adapted to be moved by said shafts V shafts of the otherel-ectroresponsive devices i of the same group, means adapted toregulate the amountof the torque exerted on said shaft by which theoperation of said switches oc curs, means adapted to lock theelectroresponsive devices against operation when one of said devices hasoperated.

V 3. The combination, in an electrical power transmission systemincluding a plurality of parallel conductorspassing in groups throughswitches, electroresponsive devices each comprising an electricmetenoperatively energized by one of said conductors, a shaftoperatively connected with said meter and adapted to be moved by saidmeter at, a speed in direct relationship with an electric quantity ofthe electricity flowing in said conductor, so that said speed beingcompelled stant predetermined ratio between each other, butincapable ofdriving said shafts, so that a shaft tending to vary its speed resultsin said torque being applied to said shaft, means controlled by saidshafts and adapted to 0p erate the switches of a group of conductorswhen the shaft of an electroresponsive device connected with a conductorof said group rotates at a speed which differs from that correspondingin the predetermined ratio to the speed of the shafts of the otherelectroresponsive devices of the same group, means adapted to regulatethe amount of the torque exerted on said shaft by which the operation ofsaid switches occurs, means adapted to lock the electroresponsivedevices against operation when one of said devices has operated,

" and means energized by an electric quantity of the electricity flowingin all of said conductors and arranged to operate all of said switcheswhen said electric quantity exceeds a predetermined value.

4. The combination, in a power supply in cluding a plurality of parallelconductors passing by groups through switches, electroresponsive deviceseach comprising-an electric meter energized by one of said conductors, ashaft arranged to be driven by said meter at a speed in directrelationship with an electric quantity of the electricity flowing insaid conductor so that its speed bein compelled to vary results in atorque applied to said shaft proportional to said quantity, a pluralityof said devices arranged in a group, a telescopic oint for connectingeach of said meters with its shaft while permitting a raising of saidshaft, a worm mounted on each of said shafts, a wheel meshing with eachof said worms and arranged to be driven by said worm, but incapable ofdriving said worm so that a shaft carrying said worm tending to vary itsspeed results in said torque beingapplied to said shaft, another shaftconnecting all of said wheels of said clectroresponsive devices of agroup with each other, and arranged to compel said wheels to rotate atspeeds which are in a constant predetermined ratio with each other, sothat a shaft rotating at a speed which is not in said predeter- 'minedratio with the speeds of the other shafts of the same group raises onaccount of its worm revolving on the gear of said wheel meshing with it,a tripping relay for each of said'switches having an energizing circuit,a pair of contacts in said circuit operated by said device tocompletesaid circuit when said electric quantity of the electricity flowing insaid conductor differs from a constant predetermined ratio with the sameelectric quantity of the electricity flowing in the other conductorsenergizing other devices of the same group, means to regulate the amountof the torque exerted on said firstnentioned shaft by which said raisingoccurs, means energized by said circuit and arranged to prevent theraising of said shafts when one of said shafts is lifted and until theswitch operated by it has completed its operation.

5. The combination, in a power supply including a plurality of parallelconductors passing by groups through switches, electroresponsive deviceseach comprising an electric ampere-hour meter energized by one of saidconductors, a shaft adapted to be driven by said meter at a speedproportional to the rate of flow of current in said conductor, aplurality of said devices in a group, a telescopic joint for connectingeach of said meters with its shaft while permitting a raisin of saidshaft, a worm mounted on said shaft, a wheel meshing with said worm andarranged to be driven by said worm, but incapable of c driving saidworm, another shaft arranged to connect all of said wheels of saidelectroresponsive devices ofa group with each other, and arranged tocompel'said wheels to rotate at speeds which are in a constantpredetermined ratio with each other, so that a meter shaft rotating at aspeed which is not in said predetermined ratio with thespeeds of theother shafts raises on account of its worm revolving on the gear of saidwheel meshing with it, a slow acting tripping relay'for each of saidswitches having an energizing circuit, a pair of contacts in saidcircuit operated by a raising of a meter shaft to complete said circuitwhen the flow of current in said conductor differs from a constantpredetermined ratio with the. flow of current in the other conductorsenergizing meters of the same group of devices, means to regulate theamount of said difference between the currents by which operation ofsaid contacts occurs, means energized by said circuit and arranged toprevent the raising of said shafts when one of said shafts is lifted anduntil the switch operated by it has completed its operation, and meansenergized by all of said conductors and arranged to operate all of saidswitches when the rate of flow of current in a conductor exceeds apredetermined value.

6. In combination, a feeder provided with several conductors arranged inparallel, a switch for said feeder, electro-responsive devi'ces'eachcomprising an electric meter energized by one of said conductors, ashaft connected with said meter and adapted to be driven by said meterat a speed in direct relationship with an electric quantity of theelectricity flowing in said conductor, so that its motion beingcompelled to vary results in a torque proportional to said quantitybeing applied to said shaft, said devices being arranged in a group,means adapted. to connect mechanically all of the shafts of said deviceswith each other, and adapted to be moved by said shafts, but beingincapable of driving said shafts, so that a shaft tending to vary itsspeed results in sai-dtorque being applied to it, means controlled bysaid shafts and adapted to operate said switch when the speeds of saidshafts differ between each other, means adapted to regulate the amountof the torque exerted on said shaftby which operation of the switchoccurs and means energized by said feeder and adapted to operate said.switch when said electric quantity of the electricity flowing in saidfeeder exceeds a predetermined value. v

7 In combination, a feeder provided with a number ofconductors arrangedin parallel, a switch for said feeder, electroresponsive devices eachcomprising an electric meter energized by one of said conductors, ashaft arranged to be driven by said meter at a speed in directrelationship with an electric quantity of the electricity flowing insaid conductors, so that its speed beingcompelled to vary results in atorque proportional to said quantity being applied to said shaft, saiddevices being arranged in a group, for connecting each of said meterswith its shaft while permitting a raising of said shaft,

a worm mounted on said shaft, a wheel arranged to be driven bysaid wormbut incapable of driving said worm, so that a shaft carrying said wormtending to vary its speed results in said torque being applied to saidshaft, another shaft arranged to connect all of said wheels of saidelectroresponsive devices with each other, and arranged to coinpel saidwheels to rotate at speeds which are in a contant predetermined ratiowith each other, so that a first mentioned shaft rotating 7 at a speedwhich is not in said predetermined ratio with the speeds of the othershafts raises on account of its worm revolving on the gear of said wheelmeshing with it, a tripping relay for each of said switches having anenergizing circuit, a pair of contactsin said circuit operated by theraising of a first mentioned shaft, and arranged to complete, saidcircuit when said electric quantity of the electricity flowing in aconductor of said feeder differs by a predetermined amount from itsnormal value which is in a constant predetermined ratio with the sameelectric quantity of the electricity flowing in the other conductors,means adapted to regulate'the amount of the torque exerted on saidrfirstmentioned shaft by which said raising occurs, and means energizedby said feeder and adapted to operate said switch when said electricquantity of the electricity flowing in said feeder exceeds apredetermined value.

8. In combination, a feeder provided with a number of conductorsarranged in parallel,

a telescopic j oint feeders being a switch for said feeder, electroresponsiie deices each comprising an electric ampere-hour meter op-erativelyenergized by one of said conductors, a shaft operatively connected withsaid meter and adapted to be moved by said meter at" a speedproportional to the rate of flow of current in said conductor, saiddevices a telescopic being arranged in a group,

said meters shaft rotatingat a speed which is not in said predeterminedratio with the speeds of the other shafts raises on account of its wormrevolving on the gear of said wheel meshing with it, a trippingrelay foreach ofsaid switches having an energizing circuit, a pair of contacts insaid circuit operated by the raising of a first mentioned shaftand'arranged to complete said circuit when the rate of flow of currentin a conductor of said feeder differs fora predetermined ratio with therate of how of current In the other conductors, means adapted toregulate the amount of said dii'erence V each conductor comprising anelectric meter energized by said conductor, a shaft connectedwith saidmeter and adapted tobe moved by said'meter at" a speed indirect'relationship with an electric quantity of the electricity flowingin said conductor so that its motion being compelled to vary results iin a torqueiproportional to said quantity being applied to said shaft, aplurality u of devices energized by conductors of different arranged toconnect mechanically all of the shafts of said devices of a group andadapted to be driven by said shafts which rotate a speeds in a constantpredetermined ratio between each other, butbeing incapable of drivingsaid shafts, so that a shafttend- 'ing to vary itsspeed results in a'torque be ing applied to said-shaft, means-controlled by said shafts andadapted to operate the at raising of I predetermined amount from itsnormal value which is in a constant arranged in a group, means saidfeeder and adapted to operate said tricquantity in the electricityflowing in switch ofa feeder-when the speed of the shaft of theelectroresponsive device connected with a conductor of said feederdiffers from said predetermined ratio with respect to the speeds of theshafts of the other devices of the same group, means adapted to regulatethe amount of the torque exerted on said shaft by which the operation'ofthe switch occurs.

10. In Combination, an electric. power transmission system including aplurality of feeders-each provided with a switch and each comprising anumber of conductors arranged in parallel, an electroresponsive devicefor each conductor comprising an electric meter energized by saidconductor, a shaft connected with said meter and adapted to be movedby-said meterat a speed in direct relationship with an electric quantityof the electricity flowing in said conductor, so that its motion beingcompelled to vary results in a torque proportional to saidquantity'being applied t'o said "haft, a pluralityof said devicesenergized by conductors of different feeders being arranged in a group,a telescopic joint for connecting each of said meters with a shaft whilepermitting a raisingof said shaft, a worm mounted on said shaft, a wheelmeshing with said worm and arranged tobe driven by said worm, butincapable of driving said worm, so that a shaft tending to vary itsspeed results in said torque being applied to said shaft, a shaft foreach group of devices, means operatively energized by said conductor andarranged to operatively connect said second mentioned shaft with saidwheel when said conductor carries an electric current, means operativelyconnected with said second shaft and said wheels and adapted to compelsaid wheels to rotate at speedsin a constant predetermined ratio witheach other, so that a first mentioned shaft rotating at'a speed which isnot in said predetermined ratio with-the speeds of the other shaftsraises on account of its worm revolving on the gear of said wheel-meshing with it, a slow acting tripping relay for each of said switcheshaving an ener- -gizing circuit, a pair of contacts in saidcir cuitoperated by the raising of a first mentioned shaftand arranged tocomplete said circuit when said electric quantity of the a conductorpassing through said switch differs from said predetermined ratio withrespect to the same elecother conductors of the same group, meansadapted to regulate the amount of the torque exerted on said firstmentioned shaft by which said raising occurs, means arranged to preventthe raising of said shafts when one of said shafts is lifted anduntilthe switch operated by it has c ompleted its operation, and meansenergized by all of said conductors and arranged to operate all of saidswitches when said tor,

shaft while permitting a with each other, so

other shafts raises on account electric quantity exceeds a predeterminedvalue.

11. The combination, transmission system including a in an electricpower plurality of feeders each provided with a switch and eachcomprising a number of conductors arranged in parallel, anelectroresponsive device for each conductor comprising an electricampere-hour meter energized by said conduca shaft connected with saidmeter and adapted to be moved by said meter at a speed proportional tothe rate of flow of current in said conductor, a plurality of saiddevices energized by conductors of different feeders being arranged in agroup, a telescopic joint for connecting each of said meters with araising of said shaft, a worm mounted on said shaft, a wheel meshingwith said worm and arranged to be driven by said worm, but incapable ofdrivmg said worm, another shaft for each group of devices, flowing insaid conductors to connect said second mentioned shaft with a wheel whenthe rate of flow of currentin said conductors exceeds apredeterminedamount, means connecting said second shaft and said wheels andadapted'to compel said wheels to rotate at speeds in a constantpredetermined ratio that a first mentioned speed which is not in saidpredetermined ratio with the speeds of the of its worm revolving on thegear of said wheel meshing with it, a slow acting tripping relay foreach of said switches including an energizing circuit, a pair ofcontacts in said circuit operated by the raising of a first mentionedshaft electromechanically connected with a conductor passing throughsaid switch, and arranged to complete said circuit when the rate of flowof current in said conductor differs by a predetermined amount from aconstant predetermined ratio with respect to the rate of flow of currentin the other conductors of the same group, means adapted to regulate theamount of said difference between the currents by which operation ofsaid contacts occurs,means energized by said circuit and arranged toprevent the raising of said shafts shaft rotating at a 'when one of saidshafts is lifted and until the means operated by the current

